go-libp2p-kad-dht/routing.go

package dht

import (
	"math/rand"
	"time"
	"encoding/json"

	proto "code.google.com/p/goprotobuf/proto"

	ma "github.com/jbenet/go-multiaddr"

	peer "github.com/jbenet/go-ipfs/peer"
	swarm "github.com/jbenet/go-ipfs/swarm"
	u "github.com/jbenet/go-ipfs/util"
)

// Pool size is the number of nodes used for group find/set RPC calls
var PoolSize = 6

// TODO: determine a way of creating and managing message IDs
func GenerateMessageID() uint64 {
	//return (uint64(rand.Uint32()) << 32) & uint64(rand.Uint32())
	return uint64(rand.Uint32())
}

// This file implements the Routing interface for the IpfsDHT struct.

// Basic Put/Get

// PutValue adds value corresponding to given Key.
func (s *IpfsDHT) PutValue(key u.Key, value []byte) error {
	var p *peer.Peer
	p = s.routes.NearestPeer(convertKey(key))
	if p == nil {
		panic("Table returned nil peer!")
	}

	pmes := pDHTMessage{
		Type: DHTMessage_PUT_VALUE,
		Key: string(key),
		Value: value,
		Id: GenerateMessageID(),
	}

	mes := swarm.NewMessage(p, pmes.ToProtobuf())
	s.network.Chan.Outgoing <- mes
	return nil
}

// GetValue searches for the value corresponding to given Key.
func (s *IpfsDHT) GetValue(key u.Key, timeout time.Duration) ([]byte, error) {
	var p *peer.Peer
	p = s.routes.NearestPeer(convertKey(key))
	if p == nil {
		panic("Table returned nil peer!")
	}

	pmes := pDHTMessage{
		Type: DHTMessage_GET_VALUE,
		Key: string(key),
		Id: GenerateMessageID(),
	}
	response_chan := s.ListenFor(pmes.Id)

	mes := swarm.NewMessage(p, pmes.ToProtobuf())
	s.network.Chan.Outgoing <- mes

	// Wait for either the response or a timeout
	timeup := time.After(timeout)
	select {
	case <-timeup:
		s.Unlisten(pmes.Id)
		return nil, u.ErrTimeout
	case resp := <-response_chan:
		pmes_out := new(DHTMessage)
		err := proto.Unmarshal(resp.Data, pmes_out)
		if err != nil {
			return nil,err
		}
		return pmes_out.GetValue(), nil
	}
}

// Value provider layer of indirection.
// This is what DSHTs (Coral and MainlineDHT) do to store large values in a DHT.

// Announce that this node can provide value for given key
func (s *IpfsDHT) Provide(key u.Key) error {
	peers := s.routes.NearestPeers(convertKey(key), PoolSize)
	if len(peers) == 0 {
		//return an error
	}

	pmes := pDHTMessage{
		Type: DHTMessage_ADD_PROVIDER,
		Key: string(key),
	}
	pbmes := pmes.ToProtobuf()

	for _,p := range peers {
		mes := swarm.NewMessage(p, pbmes)
		s.network.Chan.Outgoing <-mes
	}
	return nil
}

// FindProviders searches for peers who can provide the value for given key.
func (s *IpfsDHT) FindProviders(key u.Key, timeout time.Duration) ([]*peer.Peer, error) {
	p := s.routes.NearestPeer(convertKey(key))

	pmes := pDHTMessage{
		Type: DHTMessage_GET_PROVIDERS,
		Key: string(key),
		Id: GenerateMessageID(),
	}

	mes := swarm.NewMessage(p, pmes.ToProtobuf())

	listen_chan := s.ListenFor(pmes.Id)
	u.DOut("Find providers for: '%s'", key)
	s.network.Chan.Outgoing <-mes
	after := time.After(timeout)
	select {
	case <-after:
		s.Unlisten(pmes.Id)
		return nil, u.ErrTimeout
	case resp := <-listen_chan:
		u.DOut("FindProviders: got response.")
		pmes_out := new(DHTMessage)
		err := proto.Unmarshal(resp.Data, pmes_out)
		if err != nil {
			return nil, err
		}
		var addrs map[u.Key]string
		err = json.Unmarshal(pmes_out.GetValue(), &addrs)
		if err != nil {
			return nil, err
		}

		var prov_arr []*peer.Peer
		for pid,addr := range addrs {
			p := s.network.Find(pid)
			if p == nil {
				maddr,err := ma.NewMultiaddr(addr)
				if err != nil {
					u.PErr("error connecting to new peer: %s", err)
					continue
				}
				p, err = s.Connect(maddr)
				if err != nil {
					u.PErr("error connecting to new peer: %s", err)
					continue
				}
			}
			s.addProviderEntry(key, p)
			prov_arr = append(prov_arr, p)
		}

		return prov_arr, nil

	}
}

// Find specific Peer

// FindPeer searches for a peer with given ID.
func (s *IpfsDHT) FindPeer(id peer.ID, timeout time.Duration) (*peer.Peer, error) {
	p := s.routes.NearestPeer(convertPeerID(id))

	pmes := pDHTMessage{
		Type: DHTMessage_FIND_NODE,
		Key: string(id),
		Id: GenerateMessageID(),
	}

	mes := swarm.NewMessage(p, pmes.ToProtobuf())

	listen_chan := s.ListenFor(pmes.Id)
	s.network.Chan.Outgoing <-mes
	after := time.After(timeout)
	select {
	case <-after:
		s.Unlisten(pmes.Id)
		return nil, u.ErrTimeout
	case resp := <-listen_chan:
		pmes_out := new(DHTMessage)
		err := proto.Unmarshal(resp.Data, pmes_out)
		if err != nil {
			return nil, err
		}
		addr := string(pmes_out.GetValue())
		maddr, err := ma.NewMultiaddr(addr)
		if err != nil {
			return nil, err
		}

		return s.Connect(maddr)
	}
}